1. Field of the Invention
This invention relates generally to self-bracing three-dimensional structures of sheet material for use as camera bodies. It relates more particularly to a novel, very small structure that is fitted with a positively-interlocked single-shot shutter--to form a reliable emergency camera which can be distributed through the mails in the same manner as an advertising insert, and thereafter carried in the same manner as a credit card.
2. Prior Art
Camera bodies fabricated of sheet material appear in many patents, including U.S. Pats. Nos. 4,660,951 and 4,518,235 to Reed et al.; 4,329,037 to Caviness; 1,298,321 to Earle, 844,152 to Little; and 360,499, issued in 1887 to Whittell. Foreign patents to such constructions include French patent 623,166 to Marwitz et al. (1926), German patent 196,626 to Gutmann et al. (1906), and U. K. 8,654 to Knight et al. (1886). The Little patent, though titled "Camera", actually employs that term in its now-historical sense and shows a camera of the type used for tracing optical images.
Most of these camera bodies are plural-stage bellows, or multilayer fold-up stuctures, either not self-bracing, or not very thin. Thus the structures introduced by Reed, Earle, Whittell, Guttmann, and Knight do not appear to be self bracing. In addition, most of them seem quite bulky when folded down, although one or more might well be carried in a shirt or jacket pocket as suggested in one of the references.
While the structures of Caviness, Little and Marwitz are triangular or trapezoidal, and consequently do seem to have some self-bracing character, they are even bulkier. This latter fact may not be immediately evident from the illustrations of those respective patents--until it is recognized that the additional thicknesses introduced by the necessarily present side panels add to the total thicknesses by very large fractions.
These troublesome side panels, which are deemphasized in most of the drawings, also introduce another drawback. Structures with discrete side panels are progressively more awkward or difficult to fabricate automatically and economically (i.e., with minimal waste) from a single sheet of material.
Aside from the absence of self-bracing properties and shutter interlock, the configuration of greatest interest in regard to the present invention may be that introduced in the Reed '951 patent--particularly FIGS. 6 through 8. As can be seen in Reed's FIGS. 7 and 8, his camera folds down as only a single-stage bellows; the usage condition is created by squeezing together the two opposing edges (top left and bottom right in FIG. 7) to erect the bellows.
The result is the rectangular parallelepiped shown in Reed's FIG. 6. Unfortunately, if the user continues to squeeze the two opposing edges even more tightly they will tend to collapse inward, thereby defocusing the camera. In other words, nothing inherently limits the travel of those two opposing edges to stabilize the structure in its fully erected condition.
Another drawback of the Reed cameras, also applicable to several other patents mentioned above that purport to disclose one-picture cameras, is that the shutter is readily reopened to expose the same photosensitive medium again. In fact the medium can be reexposed as many times as a person happens to open the shutter, whether inadvertently or otherwise.
Thus Earle, for example, says, "Still another object of my invention is to produce a camera that will take but the one exposure." Upon careful reading, however, one discovers that "after the camera has been opened and a pin stuck through the paper over the opening thereof, a flap of paper will come down over this opening when the camera is again closed so that no undesirable light will passs into the camera after the exposure has been made." Of course nothing prevents unfolding Earle's camera and again moving the flap of paper.
My U.S. Pat. No. 4,846,553 for a "Foldable Viewer" may be of some interest. It is in a different field of apparatuses, but does pertain to distribution methods related to those introduced in this document.